A widespread use of personal computers and digital cameras in general households is accompanied by also a widespread use of ink-jet printers that are capable of printing vivid images in full colors aided by their low prices. However, qualities of the ordinary fine papers and coated papers are not enough for meeting the requirements of the recording papers for printing used for the ink-jet printers. The printing papers now must satisfy such requirements as quickly absorbing the ink deposited on the paper surfaces, forming vivid images by suppressing ink droplets from spreading or blurring on the paper surfaces, and offering excellent color fastness of the formed images without fading color over extended periods of time.
In order to impart such proporties to the printing surfaces (paper surfaces), proposals have been made to apply onto the surface of the paper, or fill the interior of the paper with, a variety of kinds of inorganic solid matters together with a binding agent. For instance, a patent document 1 proposes the use of a synthetic silica or a salt thereof as the inorganic solid matter, a patent document 2 proposes an art of providing the surface of a paper with a weak acid salt or an oxide of a divalent metal such as magnesium or zinc as a covering layer, a patent document 3 proposes an art of providing the surface of a paper with a covering layer that contains natural or synthetic zeolite, diatomaceous earth or synthetic mica, patent documents 4 and 5 propose arts of providing an ink-absorbing layer by using a white pigment such as clay, talc, calcium carbonate, kaolin, acid clay, or active clay, and a patent document 6 proposes an art of filling with a porous and spherical granular silicate.
With the above-mentioned conventional printing papers inclusive of those papers used for laser printers other than the ink-jet printers, however, the images that are obtained are all flat without deepness of pictorial quality.
Further, upon printing the images, the above-mentioned conventional printing papers have no function for protecting the ink components from ultraviolet rays or ozone, and are not suited for being preserved for extended periods of time.
Here, the present applicant has previously developed a sheet for printing comprising a base sheet and a printing layer formed thereon and blended with a plaster (shikkui), and has proposed it in a patent document 7.
If an image is formed by using an ink-jet printer, the above sheet for printing forms an image featuring rugged appearance, depth of pictorial quality, color fastness and vividness. Besides, the printed image has very excellent weather-proof property offering excellent advantages that could not be seen with the traditional papers for ink-jet printing.